"""Module implementing error-catching version of send (sendRobust)"""
from scrapy.xlib.pydispatch.dispatcher import Any, Anonymous, liveReceivers, getAllReceivers
from scrapy.xlib.pydispatch.robustapply import robustApply

def sendRobust(
	signal=Any, 
	sender=Anonymous, 
	*arguments, **named
):
	"""Send signal from sender to all connected receivers catching errors
	
	signal -- (hashable) signal value, see connect for details

	sender -- the sender of the signal
	
		if Any, only receivers registered for Any will receive
		the message.

		if Anonymous, only receivers registered to receive
		messages from Anonymous or Any will receive the message

		Otherwise can be any python object (normally one
		registered with a connect if you actually want
		something to occur).

	arguments -- positional arguments which will be passed to
		*all* receivers. Note that this may raise TypeErrors
		if the receivers do not allow the particular arguments.
		Note also that arguments are applied before named
		arguments, so they should be used with care.

	named -- named arguments which will be filtered according
		to the parameters of the receivers to only provide those
		acceptable to the receiver.

	Return a list of tuple pairs [(receiver, response), ... ]

	if any receiver raises an error (specifically any subclass of Exception),
	the error instance is returned as the result for that receiver.
	"""
	# Call each receiver with whatever arguments it can accept.
	# Return a list of tuple pairs [(receiver, response), ... ].
	responses = []
	for receiver in liveReceivers(getAllReceivers(sender, signal)):
		try:
			response = robustApply(
				receiver,
				signal=signal,
				sender=sender,
				*arguments,
				**named
			)
		except Exception as err:
			responses.append((receiver, err))
		else:
			responses.append((receiver, response))
	return responses
